Paper mask device

Abstract: A paper mask device (1) in which the position of longitudinal masks (2a,2b) can be changed without damaging a web of printing paper. When it is changed from the borderless printing to the printing with border, one ends of the longitudinal masks (2a,2b) are moved inwardly toward each other by means of a first transfer unit (9a) while keeping the other ends overlapped on the edges of the printing paper. A second transfer unit (9b) then operates to move the other ends of the longitudinal masks (2a,2b) inwardly to set the width of the print size. The longitudinal masks (2a,2b) can be overlapped on both edges of the printing paper without damaging it.

Description: This invention relates to a paper mask device according to the preamble of claim 1, used when negative images on a negative film are printed on a web of printing paper. Fig. 6 shows a conventional paper mask device of the type referred to above. Under a negative mask 30 holding a negative film F is provided a light source 31 which illuminates the negative film F. A negative image on the negative film F is printed on a web of printing paper A through a pair of reflective mirrors 32 and 33. In such a printing apparatus, a paper mask 34 is mounted on the web of printing paper A to set the print size. The paper mask 34 shown in Fig. 7 is known. It is provided over the web of printing paper A fed in one way and comprises a pair of longitudinal strip-like masking plates 35a and 35b, and a pair of transverse strip-like masking plates 36a and 36b. The longitudinal masking plates 35a and 35b are moved relative to each other by a single transfer unit 37, and the transverse masking plates 36a and 36b are similarly moved relative to each other by a single transfer unit 38. In each of the transfer units 37 and 38, an endless belt 41 is stretched around a pair of pulleys 39 and 40. The pulley 39 is driven by a motor 42. With the paper mask 34, when the borderless printing is to be carried out, both of the longitudinal masking plates 35a and 35b are positioned outside of both edges of the web of printing paper A. For the printing with border, the longitudinal masking plates 35a and 35b are moved toward each other to mask both edges of the printing paper A, and the transverse masking plates 36a and 36b are moved inwardly toward each other. The printing with border is then carried out. With such a conventional paper mask device, the longitudinal masking plates 35a and 35b are moved toward and away from each other. Let us suppose that the web of the printing paper is curved in a width direction as shown in Fig. 8A. When it is changed from the borderless printing to the printing with border, the longitudinal masking plates 35a and 35b, while moved inwardly toward each other, are likely to abut both edges of the web of printing paper A inwardly and damage it as shown in Fig. 8B. US 4 320 965 describes an automatic masking device for use in a printer, wherein a reproduction picture to be projected onto a photosensitive film sheet mounted on a holder is masked by a pair of masking plates, which are separated at a certain distance away from the surface of the photosensitive film sheet. The masking plates are adapted to be movable over the surface of the film sheet, so as to open and close the opening distance between the masking plates for sizing the protected picture. In this device the distance between the masking plates and the photosensitive material prevents the material from being damaged. An object of the present invention is to provide a paper mask device, and a method of its use, in which a pair of longitudinal masking plates do not damage the web of printing paper even if it is curved in a width direction. According to the present invention as defined in claim 1, there is provided a paper mask device fulfilling this need. The paper mask device comprises a pair of longitudinal masking plates provided in a longitudinal direction of a web of printing paper, and a pair of transverse masking plates provided in a transverse direction, the pair of longitudinal masking plates and the pair of transverse masks being moved relative to each other to change the print size. A first transfer unit for moving one ends of the pair of longitudinal masking plates relative to each other and a second transfer unit for moving the other ends of the pair of longitudinal masking plates relative to each other are provided, the pair of longitudinal masking plates being coupled to the first and second transfer units so that they can take oblique positions. In the paper mask device as arranged above, the borderless printing is carried out with the longitudinal masking plates positioned outside of both edges of the web of printing paper. When it is changed from the borderless printing to the printing with border by the method of claim 4, first ends of the pair of longitudinal masking plates are moved toward each other to such a position as to mask the edges of the web of printing paper by the first transfer unit; the other ends of the longitudinal masking plates are then moved toward each other by the second transfer unit so that the pair of the longitudinal masking plates will be positioned parallel to each other; and now that they mask both edges of the web of printing paper, the pair of the transverse masking plates are moved inwardly toward each other. With the paper mask device according to the present invention, when it is changed from the borderless printing to the printing with border, first ends of the longitudinal masking plates are moved inwardly while keeping the second ends overlapped on the edges of the printing paper. Thus, even if the web of printing paper is curved in a width direction, the position of the longitudinal masking plates can be changed without damaging the web of printing paper. Other features and objects of the present invention will become apparent from the following description made with reference to the accompanying drawings, in which: Fig. 1 is a perspective view showing one embodiment of the paper mask device according to the present invention; Fig. 2 is a plan view of the same; Fig. 3 is a sectional view taken along line III - III of Fig. 2; Fig. 4A is a plan view showing how the borderless printing is carried out; Fig. 4B is a plan view showing how the longitudinal masking plates are moved; Fig. 5A is a plan view showing how the longitudinal and transverse masking plates are moved; Fig. 5B is a plan view showing how the printing with border is carried out; Fig. 6 is a schematic view of the printing unit; Fig. 7 is a perspective view showing a conventional paper mask device; Fig. 8A is a sectional view of the same showing how the borderless printing is carried out; and Fig. 8B is a sectional view of the same showing the state when it is changed to the printing with border. As shown in Figs. 1 - 3, a rectangular mask frame 1 is provided therein with a pair of longitudinal masking plates 2a and 2b and a pair of transverse masking plates 3a and 3b. Each of the longitudinal masking plates 2a and 2b and the transverse masking plates 3a and 3b is in the form of a strip. The longitudinal masking plates 2a and 2b extend in a longitudinal direction of the rectangular mask frame 1 and are placed over so as to cross the transverse masking plates 3a and 3b. Inside the mask frame 1 are mounted a pair of transfer units 4a and 4b for the transverse masking plates 3a and 3b, respectively. Each of the transfer units 4a and 4b comprises an endless belt 7 stretched around a pair of pulleys 5 and 6 and a motor 8 for driving the pulley 5 to move the belt 7. Each of the transverse masking plates 3a and 3b has one end secured to the respective belt 7. But the transverse masking plates 3a and 3b may be moved toward and away from each other by a single transfer unit as in the conventional paper mask device shown in Fig. 7. Inside the mask frame 1 are mounted a first transfer unit 9a for feeding the first ends of the longitudinal masking plates 2a and 2b toward and away from each other and a second transfer unit 9b for feeding the second ends of the longitudinal masking plates 2a and 2b toward and away from each other. Each of the first and second transfer units 9a and 9b comprises an endless belt 12 stretched around a pair of pulleys 10 and 11 and a motor 13 for driving the pulley 10 to move the belt 12. Coupling pieces 14 and 15 are secured to the belt 12 on its tight side 12a and on its loose side 12b, respectively, and one ends of the longitudinal masking plates 2a and 2b are rotatably coupled to the coupling pieces 14 and 15 through pins 16, respectively. Coupling pieces 17 and 18 are similarly secured to the belt 12 on its tight side 12a and on its loose side 12b, respectively. Pins 19 are mounted on first ends of the coupling pieces 17 and 18 and inserted in pin holes 20 formed in the second ends of the longitudinal masking plates 2a and 2b, respectively. Each pin hole 20 is in the form of an elongated hole in a longitudinal direction of the longitudinal masking plates 2a and 2b. By providing the first transfer unit 9a for moving the first ends of the longitudinal masking plates 2a and 2b toward and away from each other and the second transfer unit 9b for moving the second ends of the longitudinal masking plates 2a and 2b toward and away from each other, with the first transfer unit 9a stopped, the second transfer unit 9b can operate. Thus, by moving their first ends toward or away from each other, the longitudinal masking plates 2a and 2b can form an oblique position. When the borderless printing is carried out as shown in Fig. 4A, the longitudinal masking plates 2a and 2b are positioned outside of both edges of the web of printing paper A. When it is changed from the borderless printing to the printing with border, the first transfer unit 9a is activated to move the first ends of the longitudinal masking plates 2a and 2b inwardly toward each other as shown in Figs. 4B and 5A. Then, the second transfer unit 9b is activated to move the second ends of the longitudinal masking plates 2a and 2b inwardly toward each other as shown in Fig. 5A. Now, the longitudinal masking plates 2a and 2b are positioned parallel to each other as shown in Fig. 5B and overlapped on the edges of the printing paper A. In this state, the transverse masking plates 3a and 3b, too, are moved inwardly toward each other by means of the transfer units 4a and 4b to set the length of the print size. When the position of the longitudinal masking plates 2a and 2b is changed, these masking plates have their second ends moved inwardly toward each other with their first ends already moved toward each other. Therefore, even if the web of printing paper A is curved in a width direction, the longitudinal masking plates 2a and 2b will not interfere with the edges of the web of printing paper A. Thus, the position of the longitudinal masking plates 2a and 2b can be changed without the fear of damaging the web of printing paper A.

Claims: A paper mask device (1) for determining and changing the printing size of an image printed on a web of printing paper (A), said device (1) comprising a pair of longitudinal strip-like masking plates (2a,2b) adapted to be arranged in a longitudinal direction of said web of printing paper (A), and a pair of transverse strip-like masking plates (3a,3b) adapted to be arranged in a transverse direction of said web of printing paper (A), and a transfer unit (4a,4b,9a,9b) for moving said longitudinal masking plates (2a,2b) relative to each other for increasing or decreasing the distance therebetween, and for moving said transverse masking plates (3a,3b) relative to each other for increasing or decreasing the distance therebetween, characterised in that said transfer unit includes a first transfer unit (9a) for moving the first ends of said longitudinal masking plates (2a,2b) relative to each other and a second transfer unit (9b) for moving the second ends of said longitudinal masking plates (2a,2b) relative to each other said first and second transfer units (9a,9b) are operable independently from one another, and each of said longitudinal masking plates (2a,2b) is pivotably coupled at its first and second ends to said first and second transfer units (9a,9b), respectively, so that said longitudinal masking plates (2a,2b) are adapted to take oblique positions with respect to each other. The device of claim 1, wherein said first and said second ends of each of said longitudinal masking plates (2a,2b) are pivotably connected to a coupling piece (14,15,17,18) of said first and said second transfer units, respectively, by a pin (16,19). The device of claim 2, wherein said second end of each of said longitudinal masking plates (2a,2b) includes an elongated pin hole (20) extending in the longitudinal direction of the respective masking plate (2a,2b) for receiving said pin (19). A method of determining and changing the printing size of an image printed on a web of paper (A) by means of the paper mask device of any one of claims 1 to 3, comprising the steps of: placing said web of paper (A) in said paper mask device (1); moving said first ends of said longitudinal masking plates (2a,2b) relative to each other for positioning said longitudinal masking plates (2a,2b) obliquely with respect to each other and with respect to the longitudinal direction of said web of paper (A); and thereafter moving said second ends of said longitudinal masking plates (2a,2b) relative to each other for positioning said longitudinal masking plates (2a,2b) parallel to each other and to the longitudinal direction of said web of paper (A).

Inventors: MASUTANI HIRONORI, MASUTANI, HIRONORI
Applicants: NORITSU KOKI CO LTD, NORITSU KOKI CO., LTD.
Application year: 1994
Main classification: G03B27
IPC codes: G03C5, G03B27